SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9206ab61067dd80251ea0985d6cfee03a58f9fdd319170ef2590e3ca3e47fc42' 
  AND token = 'kwWiRBEmWPnwfT6Bmj31FDSTfP1ncI3Zn3/4ve2ccRM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}